Rockwell Automation System Design for the Control of Electrical Noise - Manual (Page 64)

Publication GMC-RM001A-EN-P — July 2001
7-6 Power Distribution
Single 24V dc Switch-Mode PSU Zoning Example
In the figure below, a 24V dc supply is mounted in the dirty zone,
because it may create noise. But, the noise is reduced by filtering
before the output enters the clean zone.
Figure 7.5
24V dc power distribution with single PSU
Grounded, de-coupling capacitors are used at each clean load (refer
to the chapter High Frequency (HF) Bonding for details). Provided the
system is correctly bonded, the multiple common/ground connections
are not a problem. The copper becomes a backup conductor. No
segregation or filtering is necessary for the load in the dirty zone.
24V dc PSU
AC Filter
+24V 24V com
Dirty Zone
Clean Zone
Dirty Load
Clean Load
Segregation
De-coupling
capacitor
Filter